Cable Current-Carrying Capacity Calculator

Formula used

Corrected capacity: Iz = Iz₀ × k₁ × k₂

Copper cable current-carrying capacity table · PVC insulation (70 °C)

IEC 60364-5-52 reference values: 30 °C ambient temperature, single circuit, amperes. B2 describes a multi-core cable in conduit or trunking on a wall, C a cable fixed directly to the wall surface; values are lower in conduit inside a thermally insulated wall.

Copper cable current-carrying capacity table · XLPE insulation (90 °C)

IEC 60364-5-52 reference values: 30 °C ambient temperature, single circuit, amperes. B2 describes a multi-core cable in conduit or trunking on a wall, C a cable fixed directly to the wall surface; values are lower in conduit inside a thermally insulated wall.

Aluminum cable current-carrying capacity table · PVC insulation (70 °C)

IEC 60364-5-52 reference values: 30 °C ambient temperature, single circuit, amperes. B2 describes a multi-core cable in conduit or trunking on a wall, C a cable fixed directly to the wall surface; values are lower in conduit inside a thermally insulated wall. The standard also gives smaller aluminum cross-sections; 25 mm² and above are shown here.

Aluminum cable current-carrying capacity table · XLPE insulation (90 °C)

IEC 60364-5-52 reference values: 30 °C ambient temperature, single circuit, amperes. B2 describes a multi-core cable in conduit or trunking on a wall, C a cable fixed directly to the wall surface; values are lower in conduit inside a thermally insulated wall. The standard also gives smaller aluminum cross-sections; 25 mm² and above are shown here.

Ambient temperature correction factor (k₁)

The reference is 30 °C; at a different ambient temperature the table value is multiplied by this factor.

Grouping correction factor (k₂)

Applied by the number of equally loaded circuits of the same type laid together. For cables bunched on a surface, the factors in the bunched column also apply.

Example: 2.5 mm² copper cable, 35 °C ambient, two circuits

1. Table value: for a PVC-insulated 2.5 mm² copper cable, method B2, 3 loaded conductors, Iz₀ = 20 A.
2. Correction: k₁ = 0.94 for 35 °C and k₂ = 0.80 for two circuits; total factor 0.752.
3. Result: Iz = 20 × 0.752 = 15.04 A.

How many amps does a 1.5 mm² cable carry?

For a PVC-insulated 1.5 mm² multi-core copper cable at 30 °C ambient and a single circuit, the reference current in conduit or trunking (B2) is 15 A for a three-phase circuit (3 loaded conductors) and 16.5 A for a single-phase circuit (2 loaded conductors); laid on a wall surface (C) it is 17.5 A and 19.5 A respectively. With XLPE insulation, the same order reads 19.5 A, 22 A, 22 A and 24 A. Ambient temperatures above 30 °C and the number of circuits laid together lower these values; the protective device is selected separately.

How many amps does a 2.5 mm² cable carry?

For a PVC-insulated 2.5 mm² multi-core copper cable at 30 °C ambient and a single circuit, the reference current in conduit or trunking (B2) is 20 A for a three-phase circuit (3 loaded conductors) and 23 A for a single-phase circuit (2 loaded conductors); laid on a wall surface (C) it is 24 A and 27 A respectively. With XLPE insulation, the same order reads 26 A, 30 A, 30 A and 33 A. Ambient temperatures above 30 °C and the number of circuits laid together lower these values; the protective device is selected separately.

How many amps does a 4 mm² cable carry?

For a PVC-insulated 4 mm² multi-core copper cable at 30 °C ambient and a single circuit, the reference current in conduit or trunking (B2) is 27 A for a three-phase circuit (3 loaded conductors) and 30 A for a single-phase circuit (2 loaded conductors); laid on a wall surface (C) it is 32 A and 36 A respectively. With XLPE insulation, the same order reads 35 A, 40 A, 40 A and 45 A. Ambient temperatures above 30 °C and the number of circuits laid together lower these values; the protective device is selected separately.

How many amps does a 6 mm² cable carry?

For a PVC-insulated 6 mm² multi-core copper cable at 30 °C ambient and a single circuit, the reference current in conduit or trunking (B2) is 34 A for a three-phase circuit (3 loaded conductors) and 38 A for a single-phase circuit (2 loaded conductors); laid on a wall surface (C) it is 41 A and 46 A respectively. With XLPE insulation, the same order reads 44 A, 51 A, 52 A and 58 A. Ambient temperatures above 30 °C and the number of circuits laid together lower these values; the protective device is selected separately.

Which conditions change cable capacity?

The same cross-section carries a different current depending on PVC or XLPE insulation, surface or conduit/trunking installation, the number of loaded conductors, ambient temperature and the number of circuits side by side.

Is it enough for choosing the cross-section?

Current-carrying capacity is only the thermal criterion. Voltage drop, short-circuit withstand, protection coordination, harmonics and mechanical conditions must also be checked for the final cross-section.